Axle bending on tower

Hey guys, the shaft on our right lift/ tower is bending seemingly due to the lift hitting the mechanical stop. This causes a gear to twist (as seen in the first picture) and skip when the lift is up. However our left side is the same (as far as we can tell) and hasn’t bent once this season. Has anyone else had this happen and/ or have a solution? We thought about reducing tower spacing but states is in 5 days and our team has limited time. Sorry the lighting is bad.

It’s possible that one side of your lift is hitting the mechanical stop before the other, causing all the stress to be on that one side. I’m not sure what you could do to fix this, not really a hardware guy. Hopefully another forum member will be able to help you.

Good luck at states!

I can’t tell - is it a stop at the top or the bottom?

The second picture is a top down view of my right tower. The standoff w/ the friction padding is the mechanical stop that’s at the top, above the 60 tooth gear on my lift c-channel.

I’d reduce the padding so you have more range of motion, and add a programmatic stop to keep you from adding power to the lift after it reaches a certain height.

What about HS shafts?

Our axles were bending before we put the padding on though and there’s only 2 layers of friction padding(it’s been squished too so it’s really thin). We’ve been thinking of a programmatic stop but we have a stubborn programmer. Thanks for the additional ammunition against him :wink:

can HS shafts spin in c-channel holes?

You have to drill them out and use special bearings.

No, you have to cut them larger.

Hmm, that’s probably out of the question then.

Why do you have a physical stop? We have gotten along great this year without one. Perhaps it might be helpful to put a stop below the pivot as well, transferring force away from the axle to bending the arm. Preferably same distance away from pivot as other stop.

We zip-tied our axles together, and it removed all of our clicking problems.

Also, your second picture has some sort of optical illusion effect. It looks like the motor is mounted at the top of the c-channel, when it is two holes down. Either that or I’m too tired.

Isn’t it bad for your motors to be reversing rotation so suddenly when you’re holding a bunch of stars?

How exactly did you zip tie your axles together?

Haha it isn’t you, it does look like it.

We sorta use the fence as our stop. The arm ends up lifting the robot off the ground a little and pushing it away from the fence, wasting the energy that would have been used damaging itself over a longer period of time. We only have problems suddenly changing direction if we have objects in the claw, we release the objects before we lower our arm.

We ran zip ties from the spacers on the pinion axles to the spacers on the 60t axle.

As what I can tell, when the arm hits the back piece, all of the weight on the lift starts to create a lever, pushing the gear outward and bending the axle. Have you tried not having that stopper, and just using the fence for support? If you’re unable to do that, what about trying to move an idle 12 tooth gear on the other end, so the 60 tooth will have to push through the 12 tooth in order to bend?

That’s what I’m thinking but my confusion is why it doesn’t happen on the left side. Moving the 12 tooth is probably a good solution.

Moving the 12 tooth to the other side wouldn’t let them lower their lift though, thats why I think its behind the 60 tooth, closer to the stop

As for the shaft bending, we managed to twist a low-strength shaft until it fell apart into 2 pieces, we haven’t had an issue since we switched over to high strength shafts.

One thing I’ve done before is to use HS metal pinions instead of spacers on the axles, they kinda act as a ‘add on’ hs axle as long as you have a spacer on the outsides.